Limited amounts of arable land and adverse environmental conditions, whether natural or man made, have resulted in the use for many years of closed environment structures. These have for the most part been greenhouses of the most basic type. However, over the years methods of plant husbandry and improved structures of the greenhouse type have been constantly under development.
One relatively recent advance in controlled environment husbandry has been the use of nutrient film techniques. In general terms these techniques involve the contacting of the bottom of a plant root system with a thin stream or film of nutrient solution. The solution soaks up through the remainder of the root system by wicking or capillary action. A great many external influences affect the relatively sensitive nutrient film technique. Efforts are now underway to control various of these influences to improve both the technical aspects and the economics of the systems.
One difficulty encountered in nutrient film systems is that of adequately aerating the nutrient solution. Particularly where the solution is moved through a lengthy piping system with decreasing pipe diameters, decreasing pressure allows entrained and absorbed gases to come out of solution.
Against this background, the present invention provides for aeration of the nutrient solution just prior to introduction to plant root systems. At the same time means is provided for visually monitoring nutrient solution flow.